This invention relates to display arrangements which are capable of producing bright, readily alterable displays.
According to this invention, a display arrangement includes an evacuated envelope having a fluoroscent screen and an electron gun which is capable of producing a flood beam of electrons which falls upon said screen, the screen having three distinct adjacent localized areas which emit light of three different primary colors respectively in response to incident electrons, the electron gun comprising a cathode and a field electrode positioned adjacent to the cathode and arranged to shape the flood beam which emerges from said gun, the three localized areas of the screen being such that the undeflected flood beam falls upon one of them; means for generating a predetermined magnetic field in the region of said gun, the angle at which said beam emerges from said gun being dependent upon the polarity of the magnetic field so that said beam is deflected to fall upon the other two localized areas respectively in response to a magnetic field of the same value but of opposite polarity.
Three different localized areas of the screen can be associated with a particular flood beam and each of these areas carries a different color phosphor, e.g. red, green, blue, so that by altering the angle at which the beam emerges from the gun the color of the display can be changed. Preferably, a mesh electrode is positioned between the screen and the gun and carries a relatively low potential so that the customary very high potential which is applied to the screen does not influence the operation of the gun.